While parking, it is the object of the vehicle driver to estimate whether the parking space is large enough for parking his vehicle and whether the vehicle may be parked safely in the parking space. To make this estimation easier, conventional parking space measuring systems are used for measuring the parking space dimensions, between two parked vehicles in particular. As the vehicle drives by, distance sensors first detect a first stationary obstacle, then the length of the parking space, and then a second stationary obstacle. Subsequently, it is displayed to the driver whether his vehicle fits into the space between the obstacles. However, the driver must decide himself on the basis of this display whether he wishes to use the particular parking space for parking. It is to be taken into consideration for this purpose that, as a function of the driving skills of the driver, parking spaces of different sizes may be desired, even for the same vehicle. A comparison between the dimensions of different parking spaces is not provided. Furthermore, a measuring device must be activated even before the parking space. If a driver has driven past a parking space which is actually suitable without activating the system, he must drive past again in order to perform the measurement.